President Obama was able to formally enshrine the United States in the agreement through executive measures because he did not impose new legal obligations on the country. The United States already has a number of instruments on the books, under laws already passed by Congress to reduce carbon pollution. The country officially joined the agreement in September 2016, after submitting its request for participation. The Paris Agreement was only able to enter into force after the formal accession of at least 55 nations representing at least 55% of global emissions. This happened on October 5, 2016 and the agreement came into force 30 days later, on November 4, 2016. The Paris Agreement is an environmental agreement that was adopted by almost all nations in 2015 to combat climate change and its negative effects. The agreement aims to significantly reduce global greenhouse gas emissions in order to limit global temperature increase to 2 degrees Celsius above pre-industrial levels this century, while continuing to pursue ways to limit the increase to 1.5 degrees. The agreement provides for the commitment of all major emitters to reduce their pollution from climate change and to strengthen these commitments over time. It provides developed countries with a means to assist developing countries in their mitigation and adaptation efforts and establishes a framework for monitoring, reporting and strengthening countries` individual and collective climate goals. The language of the agreement was negotiated by representatives of 197 parties at the 21st UNFCCC Conference of the Parties in Paris and agreed on 12 December 2015.   The agreement was signed at UN Headquarters in New York from 22 April 2016 to 21 April 2017 by states and regional economic integration organisations parties to the UNFCCC (convention).  The agreement stated that it would only enter into force if 55 countries that produce at least 55% of global greenhouse gas emissions (according to a list drawn up in 2015) ratify, accept, approve or adhere to the agreement.  On April 1, 2016, the United States and China, which together account for nearly 40% of global emissions, issued a joint statement confirming that the two countries would sign the Paris Climate Agreement.
 175 contracting parties (174 states and the European Union) signed the agreement on the first day of its signing.   On the same day, more than 20 countries announced plans to join the accession as soon as possible in 2016. The ratification by the European Union has achieved a sufficient number of contracting parties to enter into force on 4 November 2016. The NDC partnership was launched at COP22 in Marrakech to improve cooperation so that countries have access to the technical knowledge and financial support they need to achieve major climate and sustainable development goals. The NDC partnership is led by a steering committee made up of industrialized and developing countries and international institutions and is supported by a support unit organized by the World Resources Institute and based in Washington, D.C. and Bonn, Germany. The NDC partnership is co-chaired by the governments of Costa Rica and the Netherlands and has 93 Member States, 21 institutional partners and 10 associate members. Turkey and three major oil-exporting nations are among the seven countries that have yet to ratify the 2015 Paris climate agreement.